FORTH GENERATION OF

PROGRAMMING LANGUAGES

MADE BY GROUP 4

GROUP MEMBERS -------

INDEX• INTRODUCTION• OBJECTIVES• LANGUAGE TOOLS• QUERY LANGUAGES• REPORT GENERATORS.• APPLICATIONS GENERATORS.• DECISION SUPPORT SYSTEMS AND FINANCIAL PLANNING

LANGUAGES.• SOME MICROCOMPUTER APPLICATION SOFTWARE.• HISTORY

INTRODUCTION

• FOURTH GENERATION LANGUAGES ARE ALSO KNOWN AS VERY HIGH LEVEL LANGUAGES. THEY ARE NON-PROCEDURAL LANGUAGES, SO NAMED BECAUSE THEY ALLOW PROGRAMMERS AND USERS TO SPECIFY WHAT THE COMPUTER IS SUPPOSED TO DO WITHOUT HAVING TO SPECIFY HOW THE COMPUTER IS SUPPOSED TO DO IT. CONSEQUENTLY, FOURTH GENERATION LANGUAGES NEED APPROXIMATELY ONE TENTH THE NUMBER OF STATEMENTS THAT A HIGH LEVEL LANGUAGES NEEDS TO ACHIEVE THE SAME RESULTS. BECAUSE THEY ARE SO MUCH EASIER TO USE THAN THIRD GENERATION LANGUAGES, FOURTH GENERATION LANGUAGES ALLOW USERS, OR NON-COMPUTER PROFESSIONALS, TO DEVELOP SOFTWARE.

OBJECTIVES OF FOURTH GENERATION LANGUAGES

• INCREASING THE SPEED OF DEVELOPING PROGRAMS.• MINIMIZING USER EFFORT TO OBTAIN INFORMATION FROM

COMPUTER.• DECREASING THE SKILL LEVEL REQUIRED OF USERS SO THAT THEY

CAN CONCENTRATE ON THE APPLICATION RATHER THAN THE INTRICACIES OF CODING, AND THUS SOLVE THEIR OWN PROBLEMS WITHOUT THE AID OF A PROFESSIONAL PROGRAMMER.

• MINIMIZING MAINTENANCE BY REDUCING ERRORS AND MAKING PROGRAMS THAT ARE EASY TO CHANGE.

LANGUAGE TOOLS FIVE BASIC TYPES OF LANGUAGE TOOLS FALL INTO THE FOURTH

GENERATION LANGUAGE CATEGORY.• QUERY LANGUAGES• REPORT GENERATORS.• APPLICATIONS GENERATORS.• DECISION SUPPORT SYSTEMS AND FINANCIAL PLANNING

LANGUAGES.• SOME MICROCOMPUTER APPLICATION SOFTWARE.

QUERY LANGUAGES

• QUERY LANGUAGES ALLOW THE USER TO ASK QUESTIONS ABOUT, OR RETRIEVE INFORMATION FROM DATABASE FILES BY FORMING REQUESTS IN NORMAL HUMAN LANGUAGE STATEMENTS (SUCH AS ENGLISH). THE DIFFERENCE BETWEEN THE DEFINITIONS FOR QUERY LANGUAGE AND FOR DATABASE MANAGEMENT SYSTEMS SOFTWARE IS SO SLIGHT THAT MOST PEOPLE CONSIDER THE DEFINITIONS TO BE THE SAME. QUERY LANGUAGES DO HAVE A SPECIFIC GRAMMAR VOCABULARY, AND SYNTAX THAT MUST BE MASTERED, BUT THIS IS USUALLY A SIMPLE TASK FOR BOTH USERS AND PROGRAMMERS.

REPORT GENERATORS

• REPORT GENERATORS ARE SIMILAR TO QUERY LANGUAGES IN THAT THEY ALLOW USERS TO ASK QUESTIONS FROM A DATABASE AND RETRIEVE INFORMATION FROM IT FOR A REPORT (THE OUTPUT); HOWEVER, IN CASE OF A REPORT GENERATOR, THE USER IS UNABLE TO ALTER THE CONTENTS OF THE DATABASE FILE. AND WITH A REPORT GENERATOR, THE USER HAS MUCH GREATER CONTROL OVER WHAT THE OUTPUT WILL LOOK LIKE. THE USER OF A REPORT GENERATOR CAN SPECIFY THAT THE SOFTWARE AUTOMATICALLY DETERMINE HOW THE OUTPUT SHOULD LOOK OR CAN CREATE HIS OR HER OWN CUSTOMIZED OUTPUT REPORTS USING SPECIAL REPORT GENERATOR COMMAND INSTRUCTIONS.

APPLICATION GENERATORS• APPLICATION GENERATORS ALLOW THE USER TO REDUCE THE TIME IT TAKES TO DESIGN AN ENTIRE SOFTWARE APPLICATION THAT ACCEPTS INPUT, ENSURES DATA HAS BEEN INPUT ACCURATELY, PERFORMS COMPLEX CALCULATIONS AND PROCESSING LOGIC, AND OUTPUTS INFORMATION IN THE FORM OF REPORTS. THE USER MUST KEY INTO COMPUTER-USEABLE FORM THE SPECIFICATION FOR WHAT THE PROGRAM IS SUPPOSED TO DO. THE RESULTING FILE IS INPUT TO THE APPLICATIONS GENERATOR, WHICH DETERMINE HOW TO PERFORM THE TASKS AND WHICH THEN PRODUCES THE NECESSARY INSTRUCTIONS FOR THE SOFTWARE PROGRAM.

DECISION SUPPORT SYSTEMS AND FINANCIAL PLANNING LANGUAGES• DECISION SUPPORT SYSTEMS AND FINANCIAL PLANNING LANGUAGES COMBINE SPECIAL INTERACTIVE COMPUTER PROGRAMS AND SOME SPECIAL HARDWARE TO ALLOW HIGH LEVEL MANAGERS TO BRING DATA AND INFORMATION TOGETHER FROM DIFFERENT SOURCES AND MANIPULATE IT IN NEW WAYS.

SOME MICROCOMPUTER APPLICATION SOFTWARE

• SOME MICROCOMPUTER APPLICATIONS SOFTWARE CAN ALSO BE USED TO CREATE SPECIALIZED APPLICATIONS – IN OTHER WORDS, TO CREATE NEW SOFTWARE. MICROCOMPUTER SOFTWARE PACKAGES THAT FALL INTO THIS CATEGORY INCLUDE MANY SPREADSHEET PROGRAMS (SUCH AS LOTUS 1-2-3), DATABASE MANAGERS (SUCH AS DBASE IV), AND INTEGRATED PACKAGES (SUCH AS SYMPHONY).

HISTORY• THOUGH USED EARLIER IN PAPERS AND DISCUSSIONS, THE TERM

4GL WAS FIRST USED FORMALLY BY JAMES MARTIN IN HIS 1982 BOOK APPLICATIONS DEVELOPMENT WITHOUT PROGRAMMERS[3] TO REFER TO NON-PROCEDURAL, HIGH-LEVEL SPECIFICATION LANGUAGES. IN SOME PRIMITIVE WAY, EARLY 4GLS WERE INCLUDED IN THE INFORMATICS MARK-IV (1967) PRODUCT AND SPERRY'S MAPPER (1969 INTERNAL USE, 1979 RELEASE).

• THE MOTIVATIONS FOR THE '4GL' INCEPTION AND CONTINUED INTEREST ARE SEVERAL. THE TERM CAN APPLY TO A LARGE SET OF SOFTWARE PRODUCTS. IT CAN ALSO APPLY TO AN APPROACH THAT LOOKS FOR GREATER SEMANTIC PROPERTIES AND IMPLEMENTATION POWER. JUST AS THE 3GL OFFERED GREATER POWER TO THE PROGRAMMER, SO TOO DID THE 4GL OPEN UP THE DEVELOPMENT ENVIRONMENT TO A WIDER POPULATION.

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